Glycogen Metabolism

Overview

Structure

• Glycogen is an extensively branched polymer of alpha-d-glucose.
  • The animal analog to starch 
  • The straight chains are alpha-1,4 links, and the branched chains are alpha-1,6 links. 
• Branching occurs every 8–10 units, making it more globular and less space consuming and allowing for increased solubility and quicker metabolization. 

Functions

• The storage form of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance, utilized when blood glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance (BG) level drops
• Muscle glycogen:
  • Available for glycolysis Glycolysis Glycolysis is a central metabolic pathway responsible for the breakdown of glucose and plays a vital role in generating free energy for the cell and metabolites for further oxidative degradation. Glucose primarily becomes available in the blood as a result of glycogen breakdown or from its synthesis from noncarbohydrate precursors (gluconeogenesis) and is imported into cells by specific transport proteins. Glycolysis in the muscle; acts as a reserve fuel for the contraction of muscles
  • Skeletal muscle itself is unable to release glycogen into the bloodstream due to a lack of glucose-6-phosphatase Glucose-6-phosphatase An enzyme that catalyzes the conversion of d-glucose 6-phosphate and water to d-glucose and orthophosphate. Gluconeogenesis (G6Pase). 
• Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy glycogen is responsible for maintaining BG levels, especially during fasting or exercise.

Storage

• The major sites of storage of glycogen are skeletal muscle and the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy:
  • Hepatic glycogen content: 10 g/100 g tissue 
  • Skeletal muscle glycogen content: 1–2 g/100 g
• The total quantity of muscle glycogen is more than liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy glycogen due to larger muscle mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast.

Metabolic pathways

There are 2 main metabolic pathways of glycogen:

1. Glycogenesis: synthesis Synthesis Polymerase Chain Reaction (PCR) of glycogen 
2. Glycogenolysis: breakdown of glycogen

Glycogenesis

Definition

• The synthesis Synthesis Polymerase Chain Reaction (PCR) of glycogen, storing excess glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance for future use
• Process is not de novo and involves the addition of glycosyl residues to already-existing glycogen molecules. 

Step 1

Isomerization of glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis to glucose-1-phosphate

• Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance addition to glycogen is initiated by the phosphorylation Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Post-translational Protein Processing of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance to glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis.
  • Enzyme converting glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance to glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis:
    • Hexokinase Hexokinase An enzyme that catalyzes the conversion of ATP and a d-hexose to ADP and a d-hexose 6-phosphate. D-glucose, d-mannose, d-fructose, sorbitol, and d-glucosamine can act as acceptors; ITP and dATP can act as donors. The liver isoenzyme has sometimes been called glucokinase. Glycolysis in the muscle 
    • Glucokinase in the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy 
  • Source of phosphate group Phosphate group Nucleic Acids: adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs triphosphate (ATP)
• Glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis is then converted to glucose-1-phosphate by the enzyme phosphoglucomutase. 
• Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + ATP → glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis → glucose-1-phosphate

Step 2

Reaction of glucose-1-phosphate with uridine triphosphate Uridine triphosphate Uridine 5′-(tetrahydrogen triphosphate). A uracil nucleotide containing three phosphate groups esterified to the sugar moiety. Purine and Pyrimidine Metabolism (UTP) to form an activated form of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance:

• Glucose-1-phosphate reacts with UTP to form an active form of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance known as uridine diphosphate Uridine diphosphate A uracil nucleotide containing a pyrophosphate group esterified to C5 of the sugar moiety. Purine and Pyrimidine Metabolism glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance (UDP-glucose).
  • Enzyme: UDP-glucose pyrophosphorylase 
  • Inorganic pyrophosphate is released in the reaction.
• Glucose-1-phosphate + UTP → UDP-glucose + pyrophosphate (PP)

Step 3

Formation of glycosidic bond Glycosidic bond Basics of Carbohydrates 

• In this step, attachment of the UDP-glucose to the hydroxyl group to the free end of a glycogen chain occurs.
  • Enzyme: glycogen synthase (rate-limiting enzyme of glycogenesis)
  • Glycogenin:
    • Classified as a glycosyltransferase
    • Core protein of the preexisting glycogen molecule to which glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance (from UDP-glucose) attaches
    • Acts as a primer to the synthesis Synthesis Polymerase Chain Reaction (PCR) of glycogen
• UDP is released in the process.
• The chain is formed via alpha-1,4-glycosidic bonds.

Step 4

Branching of glycogen:

• When a chain contains approximately 8–10 glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance units, branching follows (removing the growing chain from the nonreducing end of the chain).
• A different enzyme then “reattaches” to a neighboring chain via bonds between carbons 1 and 6 (alpha-1,6-glycosidic bond).
  • Enzyme: amylo-(1,4→1,6)-transglycosylase 
    • Also called branching enzyme
    • Similar to glucosyltransferase activity and permits chain elongation Elongation Polymerase Chain Reaction (PCR) by branching
  • Glycogen chains grow as glycogen synthase adds glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance residues and additional branches are produced.

Glycogenolysis

Definition

Breakdown of glycogen to release energy in between meals or after the depletion of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance

Step 1

Breakdown of glycogen into glucose-1-phosphate:

• Glycogen is broken down into glucose-1-phosphate by phosphorolysis.
  • Enzyme: glycogen phosphorylase (key regulatory enzyme in glycogenolysis)
  • The reaction catalyzed is similar to hydrolysis Hydrolysis The process of cleaving a chemical compound by the addition of a molecule of water. Proteins and Peptides, but a phosphate group Phosphate group Nucleic Acids is used to cleave bonds instead of water.
• Alpha-1,4-glycosidic bonds are broken from the terminal end to release glucose-1-phosphate.

Step 2

Removal of alpha-1,6-glycosidic bonds (branches):

• As glycogen is an extensively branched polymer, further processes follow to break the branches to release more glucose-1-phosphate.
• Phosphorylase hydrolyzes alpha-1,4-glycosidic bonds until only 4 glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance residues are left before the alpha-1,6 branch. 
• Further breakdown proceeds with the debranching enzyme (with a transferase and glucosidase activity).
  • 3 of the 4 glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance residues are removed, leaving 1 molecule.
  • The 3-glucose molecule chain (from the branch) is reattached to the nonreducing end of the linear chain, catalyzed by glucan transferase.
  • The single remaining molecule (in the branch) is removed by the alpha-1,6 glucosidase by hydrolysis Hydrolysis The process of cleaving a chemical compound by the addition of a molecule of water. Proteins and Peptides.
• The phosphorylase/debranching process repeats to generate glucose-1-phosphate for energy use.

Step 3

Conversion of the released glucose-1-phosphate to glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis:

• Glucose-1-phosphate is converted to glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis. 
• Enzyme: phosphoglucomutase
• Fate of glucose-6 phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes:
  • In the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy:
    • Glycogen degradation occurs to maintain BG.
    • Via a reaction catalyzed by glucose-6-phosphatase Glucose-6-phosphatase An enzyme that catalyzes the conversion of d-glucose 6-phosphate and water to d-glucose and orthophosphate. Gluconeogenesis, glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance is freed up from glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis, releasing inorganic phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes.
  • In the muscle:
    • Glycogenolysis proceeds to provide energy for muscle contraction.
    • Glucose-1-phosphate is converted to glucose-6-phosphate Glucose-6-phosphate An ester of glucose with phosphoric acid, made in the course of glucose metabolism by mammalian and other cells. It is a normal constituent of resting muscle and probably is in constant equilibrium with fructose-6-phosphate. Gluconeogenesis, which go to glycolysis Glycolysis Glycolysis is a central metabolic pathway responsible for the breakdown of glucose and plays a vital role in generating free energy for the cell and metabolites for further oxidative degradation. Glucose primarily becomes available in the blood as a result of glycogen breakdown or from its synthesis from noncarbohydrate precursors (gluconeogenesis) and is imported into cells by specific transport proteins. Glycolysis.
    • There is no glucose-6-phosphatase Glucose-6-phosphatase An enzyme that catalyzes the conversion of d-glucose 6-phosphate and water to d-glucose and orthophosphate. Gluconeogenesis in muscle, so glycogen from the muscle does not help maintain BG.
• Glycogen is also degraded in lysosomes Lysosomes A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes membrane fusion. The Cell: Organelles (via alpha-glucosidase) but does not contribute to the maintenance of BG.

Regulation of Glycogen Metabolism

Regulation overview

• Glycogen metabolism is controlled by allosteric (metabolites indicate the cellular energy state and help in modulation) and hormonal regulation. 
• Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types and different effectors coordinate to produce the appropriate effect necessary to meet the energy needs.
• The main regulatory mechanism involved is phosphorylation Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Post-translational Protein Processing, affecting the 2 main enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes:
  • Glycogen phosphorylase (activated by phosphorylation Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Post-translational Protein Processing)
  • Glycogen synthase (activated by dephosphorylation)
• The regulating hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types include:
  • Insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin (promotes glycogenesis)
  • Glucagon Glucagon A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal glucagon-like peptides. Glucagon is secreted by pancreatic alpha cells and plays an important role in regulation of blood glucose concentration, ketone metabolism, and several other biochemical and physiological processes. Gastrointestinal Secretions and epinephrine Epinephrine The active sympathomimetic hormone from the adrenal medulla. It stimulates both the alpha- and beta- adrenergic systems, causes systemic vasoconstriction and gastrointestinal relaxation, stimulates the heart, and dilates bronchi and cerebral vessels. Sympathomimetic Drugs (promote glycogenolysis)

Regulation of glycogen degradation

Glucagon Glucagon A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal glucagon-like peptides. Glucagon is secreted by pancreatic alpha cells and plays an important role in regulation of blood glucose concentration, ketone metabolism, and several other biochemical and physiological processes. Gastrointestinal Secretions and epinephrine Epinephrine The active sympathomimetic hormone from the adrenal medulla. It stimulates both the alpha- and beta- adrenergic systems, causes systemic vasoconstriction and gastrointestinal relaxation, stimulates the heart, and dilates bronchi and cerebral vessels. Sympathomimetic Drugs activate adenylate cyclase in the cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane via G proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis.

• 3’,5’-cyclic adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs monophosphate ( cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors):
  • Formed when adenylate cyclase converts ATP to cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors
  • Activates protein kinase Protein kinase A family of enzymes that catalyze the conversion of ATP and a protein to adp and a phosphoprotein. Interferons A (PKA)
• PKA:
  • Phosphorylates glycogen synthase (making it less active), thus decreasing glycogen synthesis Synthesis Polymerase Chain Reaction (PCR)
  • Phosphorylates phosphorylase kinase → activating glycogen phosphorylase b to phosphorylase a → increasing glycogenolysis
• In the muscle:
  • Calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes (Ca²⁺): activates phosphorylase kinase (which activates phosphorylase b to a)
  • Adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs monophosphate (AMP):
    • During muscle contraction: ATP → ADP → AMP
    • ↑ AMP stimulates glycogenolysis by converting phosphorylase b to phosphorylase a

Regulation of glycogen synthesis Synthesis Polymerase Chain Reaction (PCR)

• After a meal → ↑ insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin, ↓ glucagon Glucagon A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal glucagon-like peptides. Glucagon is secreted by pancreatic alpha cells and plays an important role in regulation of blood glucose concentration, ketone metabolism, and several other biochemical and physiological processes. Gastrointestinal Secretions
  • A fed state Fed state Energy Homeostasis does not activate cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors cascade (in effect, protein kinase Protein kinase A family of enzymes that catalyze the conversion of ATP and a protein to adp and a phosphoprotein. Interferons is inactive).
  • ↑ Insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin activates phosphatases Phosphatases Oxazolidinones:
    • Dephosphorylates phosphorylase kinase and phosphorylase a, making them inactive
    • Dephosphorylates glycogen synthase, which activates the enzyme and, in effect, increases glycogen synthesis Synthesis Polymerase Chain Reaction (PCR)
• In the muscle:
  • After a meal: ↓ cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors, AMP, and Ca²⁺
  • Insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin also facilitates transport of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance into muscle cells, increasing glycogen synthesis Synthesis Polymerase Chain Reaction (PCR).

Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types and glycogen metabolism

Glycogen metabolism and regulating mechanisms

Clinical Relevance

Glycogen storage disease Glycogen storage disease A group of inherited metabolic disorders involving the enzymes responsible for the synthesis and degradation of glycogen. In some patients, prominent liver involvement is presented. In others, more generalized storage of glycogen occurs, sometimes with prominent cardiac involvement. Benign Liver Tumors: a group of inherited disorders characterized by abnormalities in glycogen metabolism, resulting in an abnormal accumulation of glycogen in the tissues.